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<h1><a name="SQL-DROPTRIGGER"></a>DROP TRIGGER</h1>
<div class="REFNAMEDIV"><a name="AEN51412"></a><h2>名称</h2>DROP TRIGGER&nbsp;--&nbsp;删除一个触发器</div>
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<div class="REFSYNOPSISDIV"><a name="AEN51417"></a><h2>语法</h2>
<pre class="SYNOPSIS">DROP TRIGGER [ IF EXISTS ] <tt class="REPLACEABLE"><i>name</i></tt> ON <tt class="REPLACEABLE"><i>table</i></tt> [ CASCADE | RESTRICT ]</pre>
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<div class="REFSECT1"><a name="AEN51421"></a><h2>描述</h2>
<p><tt class="COMMAND">DROP TRIGGER</tt> 将删除所有对一个现存触发器的引用。要执行这个命令，当前用户必须是触发器的所有者。</p>
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<div class="REFSECT1"><a name="AEN51425"></a><h2>参数</h2>
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<dt><tt class="LITERAL">IF EXISTS</tt></dt>
<dd><p>如果指定的触发器不存在，那么发出一个 notice 而不是抛出一个错误。</p></dd>
<dt><tt class="REPLACEABLE"><i>name</i></tt></dt>
<dd><p>要删除的触发器名</p></dd>
<dt><tt class="REPLACEABLE"><i>table</i></tt></dt>
<dd><p>触发器定义所在的表的名称(可以有模式修饰)</p></dd>
<dt><tt class="LITERAL">CASCADE</tt></dt>
<dd><p>级联删除依赖此触发器的对象</p></dd>
<dt><tt class="LITERAL">RESTRICT</tt></dt>
<dd><p>如果有任何依赖对象存在，那么拒绝删除。这个是缺省。</p></dd>
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<div class="REFSECT1"><a name="SQL-DROPTRIGGER-EXAMPLES"></a><h2>例子</h2>
<p>删除 <tt class="LITERAL">films</tt> 表的 <tt class="LITERAL">if_dist_exists</tt> 触发器：</p>
<pre class="PROGRAMLISTING">DROP TRIGGER if_dist_exists ON films;</pre>
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<div class="REFSECT1"><a name="SQL-DROPTRIGGER-COMPATIBILITY"></a><h2>兼容性</h2>
<p>PostgreSQL 里的 <tt class="COMMAND">DROP TRIGGER</tt> 语句和 SQL 标准不兼容。在 SQL 标准里，触发器名字不是表所局部拥有的，所以命令只是简单的 <tt class="LITERAL">DROP TRIGGER <tt class="REPLACEABLE"><i>name</i></tt></tt></p>
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<div class="REFSECT1"><a name="AEN51466"></a><h2>又见</h2><a href="sql-createtrigger.html"><i>CREATE TRIGGER</i></a></div>
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